The main treatment for obesity consists of dieting and physical exercise. Diet programs may produce weight loss over the short term, but maintaining this weight loss is frequently difficult and often requires making exercise and a lower food energy diet a permanent part of a person's lifestyle.

In the short-term low carbohydrate diets appear better than low fat diets for weight loss. In the long term; however, all types of low-carbohydrate and low-fat diets appear equally beneficial. A 2014 review found that the heart disease and diabetes risks associated with different diets appear to be similar. Promotion of the Mediterranean diets among the obese may lower the risk of heart disease. Decreased intake of sweet drinks is also related to weight-loss. Success rates of long-term weight loss maintenance with lifestyle changes are low, ranging from 2–20%. Dietary and lifestyle changes are effective in limiting excessive weight gain in pregnancy and improve outcomes for both the mother and the child. Intensive behavioral counseling is recommended in those who are both obese and have other risk factors for heart disease.

Five medications have evidence for long-term use orlistat, lorcaserin, liraglutide, phentermine–topiramate, and naltrexone–bupropion. They result in weight loss after one year ranged from 3.0 to 6.7 kg over placebo. Orlistat, liraglutide, and naltrexone–bupropion are available in both the United States and Europe, whereas lorcaserin and phentermine–topiramate are available only in the United States. European regulatory authorities rejected the latter two drugs in part because of associations of heart valve problems with lorcaserin and more general heart and blood vessel problems with phentermine–topiramate. Orlistat use is associated with high rates of gastrointestinal side effects and concerns have been raised about negative effects on the kidneys. There is no information on how these drugs affect longer-term complications of obesity such as cardiovascular disease or death.

The most effective treatment for obesity is bariatric surgery. The types of procedures include laparoscopic adjustable gastric banding, Roux-en-Y gastric bypass, vertical-sleeve gastrectomy, and biliopancreatic diversion. Surgery for severe obesity is associated with long-term weight loss, improvement in obesity related conditions, and decreased overall mortality. One study found a weight loss of between 14% and 25% (depending on the type of procedure performed) at 10 years, and a 29% reduction in all cause mortality when compared to standard weight loss measures. Complications occur in about 17% of cases and reoperation is needed in 7% of cases. Due to its cost and risks, researchers are searching for other effective yet less invasive treatments including devices that occupy space in the stomach.

As of 2015 there is not good evidence comparing surgery to lifestyle change for obesity in children. There are a number of high quality ongoing studies looking at this issue.

Schools play a large role in preventing childhood obesity by providing a safe and supporting environment with policies and practices that support healthy behaviors. At home, parents can help prevent their children from becoming overweight by changing the way the family eats and exercises together. The best way children learn is by example, so parents should lead by example by living a healthy lifestyle. Screening for obesity is recommended in those over the age of six.

The usual treatments for overweight individuals is diet and physical exercise.

Dietitians generally recommend eating several balanced meals dispersed through the day, with a combination of progressive, primarily aerobic, physical exercise.

Because these general treatments help most case of obesity, they are common in all levels of overweight individuals.

School nurses in Uppsala, Uppsala County will be prescribing exercise to teenage boys. The prescribed exercise can be anything from participating in a sport to walking. Spaces will be available for the participants.

A 2016 review supported excess food as the primary factor. Dietary energy supply per capita varies markedly between different regions and countries. It has also changed significantly over time. From the early 1970s to the late 1990s the average food energy available per person per day (the amount of food bought) increased in all parts of the world except Eastern Europe. The United States had the highest availability with per person in 1996. This increased further in 2003 to . During the late 1990s Europeans had per person, in the developing areas of Asia there were per person, and in sub-Saharan Africa people had per person. Total food energy consumption has been found to be related to obesity.

The widespread availability of nutritional guidelines has done little to address the problems of overeating and poor dietary choice. From 1971 to 2000, obesity rates in the United States increased from 14.5% to 30.9%. During the same period, an increase occurred in the average amount of food energy consumed. For women, the average increase was per day ( in 1971 and in 2004), while for men the average increase was per day ( in 1971 and in 2004). Most of this extra food energy came from an increase in carbohydrate consumption rather than fat consumption. The primary sources of these extra carbohydrates are sweetened beverages, which now account for almost 25 percent of daily food energy in young adults in America, and potato chips. Consumption of sweetened drinks such as soft drinks, fruit drinks, iced tea, and energy and vitamin water drinks is believed to be contributing to the rising rates of obesity and to an increased risk of metabolic syndrome and type 2 diabetes. Vitamin D deficiency is related to diseases associated with obesity.

As societies become increasingly reliant on energy-dense, big-portions, and fast-food meals, the association between fast-food consumption and obesity becomes more concerning. In the United States consumption of fast-food meals tripled and food energy intake from these meals quadrupled between 1977 and 1995.

Agricultural policy and techniques in the United States and Europe have led to lower food prices. In the United States, subsidization of corn, soy, wheat, and rice through the U.S. farm bill has made the main sources of processed food cheap compared to fruits and vegetables. Calorie count laws and nutrition facts labels attempt to steer people toward making healthier food choices, including awareness of how much food energy is being consumed.

Obese people consistently under-report their food consumption as compared to people of normal weight. This is supported both by tests of people carried out in a calorimeter room and by direct observation.

A permanent routine of exercise, eating healthily, and, during periods of being overweight, consuming the same number or fewer calories than used will prevent and help fight obesity. A single pound of fat yields approximately 3500 calories of energy (32 000 kJ energy per kilogram of fat), and weight loss is achieved by reducing energy intake, or increasing energy expenditure, thus achieving a negative balance. Adjunctive therapies which may be prescribed by a physician are orlistat or sibutramine, although the latter has been associated with increased cardiovascular events and strokes and has been withdrawn from the market in the United States, the UK, the EU, Australia, Canada, Hong Kong, Thailand, Egypt and Mexico.

A 2006 study published in the International Journal of Sport Nutrition and Exercise Metabolism, suggests that combining cardiovascular (aerobic) exercise with resistance training is more effective than cardiovascular training alone in getting rid of abdominal fat. An additional benefit to exercising is that it reduces stress and insulin levels, which reduce the presence of cortisol, a hormone that leads to more belly fat deposits.

Self-motivation by understanding the risks associated with abdominal obesity is widely regarded as being far more important than worries about cosmetics. In addition, understanding the health issues linked with abdominal obesity can help in the self-motivation process of losing the abdominal fat. As mentioned above, abdominal fat is linked with cardiovascular disease, diabetes, and cancer. Specifically it's the deepest layer of belly fat (the fat you cannot see or grab) that poses health risks, as these "visceral" fat cells produce hormones that can affect health (e.g. increased insulin resistance and/or breast cancer risk). The risk increases considering the fact that they are located in the proximity or in between organs in the abdominal cavity. For example, fat next to the liver drains into it, causing a fatty liver, which is a risk factor for insulin resistance, setting the stage for Type 2 diabetes.

In the presence of diabetes mellitus type 2, the physician might instead prescribe metformin and thiazolidinediones (rosiglitazone or pioglitazone) as antidiabetic drugs rather than sulfonylurea derivatives. Thiazolidinediones may cause slight weight gain but decrease "pathologic" abdominal fat (visceral fat), and therefore may be prescribed for diabetics with central obesity.

Thiazolidinedione has been associated with heart failure and increased cardiovascular risk; so it has been withdrawn from the market in Europe by EMA in 2010.

Low-fat diets may not be an effective long-term intervention for obesity: as Bacon and Aphramor wrote, "The majority of individuals regain virtually all of the weight that was lost during treatment." The Women's Health Initiative ("the largest and longest randomized, controlled dietary intervention clinical trial") found that long-term dietary intervention increased the waist circumference of both the intervention group and the control group, though the increase was smaller for the intervention group. The conclusion was that mean weight decreased significantly in the intervention group from baseline to year 1 by 2.2 kg (P<.001) and was 2.2 kg less than the control group change from baseline at year 1. This difference from baseline between control and intervention groups diminished over time, but a significant difference in weight was maintained through year 9, the end of the study.

Although there are many short- term preventative methods in place to combat childhood, there are some individuals who return to their initial base weight and therefore might turn to surgical measures to achieve a more lasting effect. Bariatric surgery is an effective procedure used to restrict the patients food intake and decrease absorption of food in the stomach and intestines. Proecdures of this type are said to be able to reduce excess body weight of obese or overweight individuals by 50-75%, ultimately maintaining this weight loss for 16 years following.

As much as 64% of the United States' adult population is considered either overweight or obese, and this percentage has increased over the last four decades.

Several studies have shown that obese men tend to have a lower sperm count, fewer rapidly mobile sperm and fewer progressively motile sperm compared to normal-weight men.

Obesity in Germany has created a cholesterol problem. High cholesterol is known to cause premature death, angina, heart disease and strokes.

There has been an increase of children with Type 1 diabetes between 1996 and 2011. Diabetics are at higher risk for complications such as heart attack and stroke. In Germany, 600,000 people suffered from diabetes near the end of World War II compared to eight million now.

Obesity can increased risk for secondary diseases such as diabetes, cardiovascular disease, certain cancers and Alzheimer's. Children who get diabetes can expect to lose 10 to 15 years off of their lives. Diabetes also affect the eyes, kidneys and nerves in the legs.

Obesity is a "very strong promoter of cancer." Obesity causes an increased risk for colon cancer and breast cancer.

Weight management has two steps: weight loss and weight maintenance. In the weight loss phase, energy intake from food must be less than the energy expended each day. Achieving weight loss in cats and dogs is challenging, and failure to lose weight is common.

Medical treatments have been developed to assist dogs in losing weight. Dirlotapide (brand name Slentrol) and mitratapide (brand name Yarvitan) were authorized for use in the EU by the European Medicines Agency for helping weight loss in dogs, by reducing appetite and food intake, but both of these drugs have been withdrawn from the market in the EU. The US Food and Drug Administration approved dirlotapide in 2007. Up to 20% of dogs treated with either dirlotapide or mitratapide experience vomiting and diarrhea; less commonly, anorexia may occur. When these drugs are stopped, the dog's appetite returns to previous levels. If other weight-loss strategies are not employed, the dog will again gain weight.

This is a list of the states of India ranked in order of percentage of people who are overweight or obese, based on data from the 2007 National Family Health Survey.

A high consumption of beer and food, fatty foods and a lack of physical activity are to be blamed for obesity in Germany.

Another issue is the lack of Mediterranean lifestyle and diet. Children's food products do not contribute to a healthy diet.

Die Welt reported that a "balanced diet is practically impossible." The profit margin for fruits and vegetables was below five percent while confectionery, soft drinks and snacks was at 15% or more.

Blame has been put on fast food, prepared food, the widespread presences of unhealthy snacks, sedentary lifestyle and the loss of "common food culture". The French tradition of not opening the refrigerator between meals for a child isn't as prevalent it once was. Fat content in the French diet has increased steadily to the point where it is predicted that obesity-related diseases will start to increase.

The French connect food to pleasure and they enjoy eating, considering meals a celebration of their cuisine.

Several studies have shown that obese men tend to have a lower sperm count, fewer rapidly mobile sperm and fewer progressively motile sperm compared to normal-weight men. Researchers in France have said that poor children were up to three times more likely to be obese compared with wealthier children.

In French society, the main economic subgroup that is affected by obesity is the lower class so they perceive obesity as a problem related to social inequality.

According to Cleveland Clinic, cultural, social, and environmental factors, among others, all affect eating behaviors.

Obesity in the United States has been increasingly cited as a major health issue in recent decades, resulting in diseases such as coronary heart disease that lead to mortality. While many industrialized countries have experienced similar increases, obesity rates in the United States are the highest in the world.

Obesity has continued to grow within the United States. Two of every three American men are considered to be overweight or obese, but the rates for women are far higher. The United States contains one of the highest percentage of obese people in the world. An obese person in America incurs an average of $1,429 more in medical expenses annually. Approximately $147 billion is spent in added medical expenses per year within the United States. This number is suspected to increase approximately $1.24 billion per year until the year 2030.

The United States had the highest rate of obesity within the OECD grouping of large trading economies. From 23% obesity in 1962, estimates have steadily increased. The following statistics comprise adults age 20 and over. The overweight percentages for the overall US population are higher reaching 39.4% in 1997, 44.5% in 2004, 56.6% in 2007, and 63.8% (adults) and 17% (children) in 2008. In 2010, the Centers for Disease Control and Prevention (CDC) reported higher numbers once more, counting 65.7% of American adults as overweight, and 17% of American children, and according to the CDC, 63% of teenage girls become overweight by age 11. In 2013 the Organisation for Economic Co-operation and Development (OECD) found that 57.6% of American citizens were obese. The organization estimates that 3/4 of the American population will likely be overweight or obese by 2020. The latest figures from the CDC as of 2014 show that more than one-third (36.5%) of U.S. adults age 20 and older and 17% of children and adolescents aged 2–19 years were obese. A second study from the National Center for Health Statistics at the CDC showed that 39.6% of US adults age 20 and older were obese as of 2015-2016 (37.9% for men and 41.1% for women).

Obesity has been cited as a contributing factor to approximately 100–400 000 deaths in the United States per year and has increased health care use and expenditures, costing society an estimated $117 billion in direct (preventive, diagnostic, and treatment services related to weight) and indirect (absenteeism, loss of future earnings due to premature death) costs. This exceeds health care costs associated with smoking and accounts for 6% to 12% of national health care expenditures in the United States.

Compared to non-obese animals, obese dogs and cats have a higher incidence of osteoarthritis (joint disease) and diabetes mellitus, which also occur earlier in the life of the animal. Obese animals are also at increased risk of complications following anesthesia or surgery.

Obese dogs are more likely to develop urinary incontinence, may have difficulty breathing, and overall have a poorer quality of life compared to non-obese dogs, as well as having a lower life expectancy. Obese cats have an increased risk of diseases affecting the mouth and urinary tract. Obese cats which have difficulty grooming themselves are predisposed to dry, flaky skin and feline acne.

The causes of childhood obesity can be based on both a combination of individual choices and socio-environmental adaptions with genetic factors playing an important role also.

Several studies have shown that obese men tend to have a lower sperm count, fewer rapidly mobile sperm and fewer progressively motile sperm compared to normal-weight men.

Obesity has been observed throughout human history. Many early depictions of the human form in art and sculpture appear obese. However, it was not until the 20th century that obesity became common — so much so that, in 1997, the World Health Organization (WHO) formally recognized obesity as a global epidemic. Obesity is defined as having a body mass index (BMI) greater than or equal to 30 kg/m, and in June 2013 the American Medical Association classified it as a disease, with much controversy.

In countries of the Organisation for Economic Co-operation and Development (OECD), one child out of five is overweight or obese. Once considered a problem only of high-income countries, obesity rates are rising worldwide. Globally, there are now more people who are obese than who are underweight, a trend observed in every region over the world except parts of sub-Saharan Africa and Asia. In 2013, an estimated 2.1 billion adults were overweight, as compared with 857 million in 1980. Of adults who are overweight, 31% are obese. Increases in obesity have been seen most in urban settings.

Since body fat can be measured in several ways, statistics on the epidemiology of obesity vary between sources. While BMI is the most basic and commonly used indicator of obesity, other measures include waist circumference, waist-to-hip ratio, skinfold thicknesses, and bioelectrical impedance. The rate of obesity increases with age at least up to 50 or 60 years old.

The OECD notes that — given the health, economic, and social consequences of obesity — many countries have built multi-stakeholder networks involving civil society and the business sector in order to devise appropriate public health policies and solutions for obesity prevention.

Causes cited for the growing rates of obesity in the United Kingdom are multiple and the degree of influence of any one factor is often a source of debate. At an individual level, a combination of excessive food energy intake and a lack of physical activity is thought to explain most cases of obesity. Reduced levels of physical activity due to increased use of private cars, desk bound employment, a decline in home cooking skills and the ready availability of processed foods high in sugar, salt and saturated fats, are variously cited as contributing factors.

Obesity in the United Kingdom is a significant contemporary health concern, with officials stating that it is one of the leading preventable causes of death. In February 2016, Health Secretary Jeremy Hunt described rising rates of childhood obesity as a "national emergency".

Data published as a part of the World Health Organisation (WHO) study in 2014 indicated that 28.1% of adults in the United Kingdom were recognised as clinically obese with a Body Mass Index (BMI) greater than 30. In 2014 62% of adults in England were classified as overweight (a body mass index of 25 or above) or obese, compared to 53% 20 years earlier. More than two-thirds of men and almost six in 10 women are overweight or obese.

Experts have predicted that by the year 2020 one third of the United Kingdom population could be obese. Rising levels of obesity are a major challenge to public health. There are expected to be 11 million more obese adults in the UK by 2030, accruing up to 668,000 additional cases of diabetes mellitus, 461,000 cases of heart disease and stroke, 130,000 cases of cancer, with associated medical costs set to increase by £1.9–2.0B per year by 2030. Adult obesity rates have almost quadrupled in the last 25 years.

For children, data from the Health Survey for England (HSE) conducted in 2014 and examining patterns of overweight and obesity among children aged 2–15, showed that 17% of children were obese and an additional 14% of children were overweight.

Combing three years of data (2012, 2013 and 2014) Public Health England identified Barnsley, South Yorkshire as the local authority with the highest incidence of adult obesity (BMI greater than 30) with 35.1%. Data from the same study revealed that Doncaster, South Yorkshire was the local authority with the highest overall excess weight with 74.8% of adults (16 years and over) with a BMI greater than 25. In previous Public Health England studies based on 2012 data, Tamworth in Staffordshire had been identified as the fattest town in England with a 30.7% obesity rate.

50% of men and 70% of women in the United States between the ages of 50 and 79 years now exceed the waist circumference threshold for central obesity.

When comparing the body fat of men and women it is seen that men have close to twice the visceral fat as that of pre-menopausal women.

Central obesity is positively associated with coronary heart disease risk in women and men. It has been hypothesized that the sex differences in fat distribution may explain the sex difference in coronary heart disease risk.

There are sex-dependent differences in regional fat distribution. In women, estrogen is believed to cause fat to be stored in the buttocks, thighs, and hips. When women reach menopause and the estrogen produced by ovaries declines, fat migrates from their buttocks, hips, and thighs to their belly.

Males are more susceptible to upper-body fat accumulation, most likely in the belly, due to sex hormone differences.

Abdominal obesity in males is correlated with comparatively low testosterone levels. Testosterone administration significantly increased thigh muscle area, reduced subcutaneous fat deposition at all levels measured, but slightly increased the visceral fat area.

Even with the differences, at any given level of central obesity measured as waist circumference or waist to hip ratio, coronary artery disease rates are identical in men and women.

Obesity rates in Italian two-year-olds are the highest in Europe with a rate of 42%. Causes are lack of a Mediterranean diet and lifestyle choices such as exercise and getting enough sleep.